We were the first people who stayed at Pum's apartment. We recommend that place without any hesitiation. Here are some details.
Though apartment is located very close (5 minutes walk) to Wutthakat BTS station we were using mostly taxis or uberpop.. The latter is recommended due to issues with taxi drivers who refuse to turn taxi meter on - for us (two pairs) it was the cheapest and fastest way to move around the city. With one exception - traffic in Bangkok can be huge (i.e. around 4-5 pm).
The apartment itself is located at 20th flooor with access to the pool, sauna and fitness room (at 5th floor). It has two separate ACs (when we arrived there was over 30 degrees Celsius at day and night!). In the kitchen you'll find fridge, kettle, generally all the amenities that you'll need. Pum even supplied the fridge with foods like bread, eggs, cheese etc which you can pay for when leaving. In the bathroom you'll find also cosmetics, just like in a good hotel. Near BTS station you'll find 7 Eleven (24h) and some food stalls.
Pum was very helpful, we were still in touch with her using Line messenger app. I think that she could help you with any issue or question that you may have during your stay. We would like to thank Pum for her true hospitality!